Tunnel airboat



Mar. 5, 1929. K. M. E. ZWINKE'L TUNNEL AIRBOAT Filed Aug. 11, 1928 2 Sheets-Sheet wumatoz dttozmq Mar. 5, 1929. K. M. E. ZWINKEL TUNNEL AIRBOA'I Filed Aug. 11, 1928 2 SheetsSheet 2 Patented Mar. 5, 1929 UNITED STATES 1,703,916 PATENT orrics.

KARL MAX ERICH ZWINKEL, F DENVILLE, NEW JERSEY.

TUNNEL AIRBOAT.

Application filed August 11, 1928. Serial No. 299,045.

The invention relates to an airplane preferably adapted for emergency use as a boat upon the water as well asfor flying in the air. One of the objects of the invention is to increase the efiiciency of the motors employed for driving the propellers and thereby increase the possible speed of the airplane.

A further object of the invention is to render the motors and propellers-accessible from the interior of the machine at all times and in all conditions of weather.

These results are accomplished by providing one or more tubes extending longitudinally of the machine with which tubes a plurality of motor driven propellers communicate.

In the preferred form a single centrally arranged tube is employed and two rows of propellers communicate with the tube. These propellers are so arranged that the compression within the tube increases gradually from front torear. To accomplish this the speed of rotation of the propellers progressively increases from front to rear, and-also the pitch of the propellers increases progressively from front to rear.

The invention may be more readily understood by reference to the accompanying drawings in which Fig. 1 is a side elevation showing an airplane equipped with a preferred form of my invention. s

Fig. 2 is atop plan view of the same.

Fig. 3 is a vertical sectional view through the machine showing the arrangement of motors and the central longitudinal tube.

Fig. 4 is a fra mentary side elevation on an enlar ed scale showing one of the propellers and t e motor for operating thesame, and also showing a slot leading from the exterior of the machine to the central tube.

Fig. 5 is a detailed sectional view showing a modification in which a full tube is employed and in which the ropellers are mount- 'ed' wholly within the to. e.

Referring to the drawings in detail, the ref- 7 erence numeral 10 designates the hollow body of. anairplane which is preferably boatshaped, and water-tight so as to permit of emergency use as a boat. This boat is preferably of metallic construction, alight metal,

such as aluminum,being employed. The de-- vice is equipped with common wings indicated at 11, the present device being shown as of the monoplane type, although anynuinv her of wings may belemplo ed.

Within t e body of the oat are-freight,

fuel and passenger compartments which are entirely protected from the weather. These are indicated at 12, 12a, 13 and 14.

The important feature of the invention resides in the provision of a longitudinal tube 15 which extends the entire length of the machine from front to rear. The arrangement shown in Figs. 1 to 4 is of the half tube type and is centrally arranged. If desired, more than one tube may be employed, as for example Where two tubes are used, one on each side of the body of the machine. I Means are provided for progressively increasing the compression from front to rear within the longitudinal tube. As shown in Figs. 1 to 4,.two rows of sin le motors and propellers operated thereby are employed. Une of these propellers is shown in detail in Fig. 4, and is desi nated by the numeral 16. A slot 17 in the body of the machine provides a means of communication between the outer atmosphere and the longitudinal tube and the propeller operates within this slot. Each propeller is actuted by a suitable motor 18, herein shown as located at the rear of its respective propeller.

As shown in Fig. 2, the propellers in the two rows are staggered. In order to provide for gradually increasing the compression from the foremost propeller to the one at the rear, the speed of rotation of the propellers is preferably gradually increasing from front to rear and in addition the pitch should be progressively increasing from front to rear. The desired result might be accomplished b having all motors rotate at the same spee but with progressively increasing pitch or by having the pitch of all of the propellers the same, but with progressively increasing speed. The referred arrangement, however, is with 0th. speed and pitch progressively increasin from front to rear.

Referring to ig. 3, it will be noted that due to the form of the central tube which has inset portions at 19, the propellers may be mounted so as to obtain maximum eficiency.

It will also be noted that spaces are provided at 20 which are in direct communication with the passenger compartment 13, through whichspaces access may be had to the propellers and motors without exposure to the weather.

While in my preferred formI have shown the propellers rotating artially within the central tube and partial y in the outside atmosphere, it is possibleto have the propellers located entirely within a central tube, as

shown in Fig.. 5, in which I have emplo ed what I term as a full tube 21, as distinguis ed from the half tube 15 shown in Fig. 3, employed in the preferred embodimentof the invention. The advantage of the half tube arrangement resides in the fact that by having t e propeller rotate in the outside atmosphere as well as in the tube, back draft is prevented and thus greater eflieiency is secured. I do not wish, however, to confine my invention to this arrangement, or to the use of a single tube.

The. airplane may be equipped with the usual horizontal and vertical air rudders 22 and 23 and in addition an extension 24 from the vertical rudder 23 may be 'rovided making the device more efficient or use on the water.

. What I claim as new and desire to secure by Letters Patent is 1.- An airplane compnsing a hollow metal body, a central tube extending longitudinally from front to rear of said body, a plurality of said body, and a plurality of propellers mounted in two rows, one row on each side of-the tube, and in staggered relation to each other.

4. An airplane comprising a body, a central tube extendin longitudinally from front to rear of said bo y, a plurality of propellers mounted in two rows, one row on each side of the central tube, and in staggered relation to each other.

In'testimon whereof I afiix my signature.

KARL X ERICH ZWINKEL. 

